The Federal Bureau of Investigation said on Wednesday that it had disrupted progress made by Russian military hackers in the United States. Officials said that communication infrastructure and devices were hijacked by the federal body.

The operation was described as a “pre-emptive move” to block the Russian hackers from engaging compromised devices into a “botnet”, a network of hacked devices that can push rogue traffic to selected servers. The details about the FBI operation were acquired from an unsealed redacted affidavit, according to reports from Reuters.

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Cyclops Blink, a malware that was linked to the Russian military’s intelligence services, was used to control the botnet network. The United States and the United Kingdom have connected the Cyclops Blink to “Sandworm”, a Russian hacking group.

Merrick Garland, the Attorney General of the United States, said in a statement, “Fortunately, we were able to disrupt this botnet before it could be used”, according to reports from Reuters.

WatchGuard Technologies, an international network safety provider, confirmed that the United States Department of Justice also worked with the company to disrupt the hackers. However, the organisation did not reveal how many devices were affected by the operation.

Chris Wray, the current director of the United States Federal Bureau of Investigation, said in a statement to Reuters, “We removed malware from devices used by thousands of mostly small businesses for network security all over the world.”

“We shut the door the Russians had used to get into them”, the FBI director added.

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The operation took place as the United States and other Western allies have announced a flurry of sanctions on the Kremlin as reports of possible war crimes emerge from Ukraine. 

The latest sanctions block all new American investments in Russia and even target family members of Russian officials, including the two daughters of President Vladimir Putin.